Replaceable flow-control assembly for use in a fluid flow line

ABSTRACT

A single-piece flow-control assembly is configured to be disposed within a pit assembly in a manner which allows the flow-control assembly to be easily and quickly removed and replaced. The flow-control assembly includes one or more regulators rigidly connected to a mounting assembly having two coupling mechanisms adapted to rigidly mount to at least one of a fluid inlet pipe or a fluid outlet pipe at locations away from the ends of these pipes. The coupling mechanisms provide a sealed engagement between the ends of the flow-control assembly and the fluid inlet pipe and the fluid outlet pipe when the flow-control assembly is properly installed within the pit assembly. A fluid passageway with a 180 degree bend therein may be provided as part of the flow-control assembly so that the coupling mechanisms simultaneously couple to or decouple from the fluid inlet and outlet pipes by movement of the flow-control assembly in one direction.

RELATED APPLICATION

This is a continuation in part of patent application Ser. No.08/968,325, filed Nov. 12, 1997, now U.S. Pat. No. 5,975,122, issuedNov. 2, 1999, which is based on and claims benefit from provisionalapplication Ser. No. 60/031,371, filed Nov. 19, 1996.

TECHNICAL FIELD

The present invention relates generally to fluid flow lines and, moreparticularly, to a flow-control assembly having fluid flow controlcomponents that can be easily removed from and inserted into a fluidflow line.

BACKGROUND OF THE ART

Fluid flow systems, such as natural gas distribution systems, include anetwork of fluid flow lines that distribute fluid from a fluid source,such as a gas provider, to a number of individual users at, for example,houses, apartment buildings, etc. Typically, the fluid flow linesassociated with a gas distribution system are disposed underground andhave regulators, valves and/or other fluid flow control componentsdisposed at advantageous control points within the lines. The controlcomponents regulate the flow of gas from a high-pressure side associatedwith the fluid provider to a low-pressure side associated with a fluiduser.

To aid in the maintenance of, for example, gas lines, the regulators,valves and other components at a control point are disposed inabove-ground stations or pit assemblies that allow access to thesecomponents. Pit assemblies are usually located underground and are largeenough so that a service person can enter the pit assembly to access,test, repair and/or replace the regulators or other flow controlcomponents within the pit assembly.

In a standard configuration, each pit assembly includes two sets ofredundant regulators connected in parallel between a gas inlet (coupledto a gas provider) and a gas outlet (coupled to a gas user). One ofthese sets of regulators comprises a main flow line that is used tocontrol fluid flow during normal operation of the gas system while theother set of regulators comprises a backup line that remains unusedwhile the main line is operational. In another standard configuration,two pit assemblies are placed in series separated by a length of pipe,per local requirements, with one set of regulators in each pit assembly.During operation, one of these sets of regulators may be used toactively control fluid flow during normal operation of the gas systemwhile the other set of regulators may comprise a backup line thatmonitors flow when the active set is operational (a worker/monitorset-up). Alternatively, both of these sets of regulators may be used tocontrol fluid flow during normal operation so as to maintain anintermediate pressure between the pit assemblies (a series regulatorset-up). In either of these cases, by-pass lines would be included toallow isolation of the regulator sets from the main line.

When one or more of the regulators or other components associated withthe main line needs to be tested, repaired or replaced, the backup orby-pass line is switched into use to provide a constant flow of gas tothe gas users. Thereafter the main line is disassembled and thecomponents thereof are tested, repaired or replaced as necessary. Thisdisassembly procedure can take a significant amount of time due to thenumber of nuts, bolts, and other fasteners which must be removed todisassemble the components of the main line. During this time, surfacetraffic flow around the installation may be disrupted. Furthermore,removal of components of either the main line or the backup line isimpaired by the limited amount of space within the pit assembly and bythe hard-to-reach nature of some of the components within the pitassembly. Sometimes, special precautions must also be taken beforeentering a pit assembly to perform test, repair, or maintenance work.Such precautions may include venting the pit assembly, which requires anexternal air supply and adds to the time and cost associated withperforming maintenance. It is desirable to reduce the size of a pitassembly and to make fluid flow lines less expensive to build andfaster, safer and easier to maintain.

SUMMARY OF THE INVENTION

The present invention is directed to a flow-control assembly disposedwithin a pit assembly in a manner which allows the flow-control assemblyto be easily and quickly removed and replaced without requiring aservice person to actually enter or crawl down into a pit assembly. Thisflow-control assembly also enables a pit assembly to be reduced in sizebecause the pit assembly does not need to provide space for a serviceperson to enter the pit assembly. Smaller pit assembly size means lessspace is required for installation and may help to reduce installedstation cost. Reduced pit assembly size also eliminates the possibilityof a service person entering a pit assembly which removes the dangersassociated with entering confined spaces.

According to one aspect of the present invention, a flow-controlassembly includes one or more rigidly connected fluid controlcomponents, such as regulators, valves etc., and coupling mechanismsdisposed on each end thereof. The coupling mechanisms are configured toengage a fluid inlet pipe and a fluid outlet pipe within a pit assemblyin a sealed manner. Preferably, the coupling mechanisms comprise femaleor male coupling ends that mate with male or female coupling endsdisposed on the fluid inlet and outlet pipes. If desired, the seal maybe provided by an O-ring seal disposed in, for example, the femalecoupling ends.

In one embodiment, the flow-control assembly includes a fluid passagewaywith a 180 degree bend therein so that the coupling ends on each end ofthe flow-control assembly simultaneously couple to or decouple from thecoupling ends disposed on the fluid inlet and outlet pipes by movementof the flow-control assembly in one direction.

The flow-control assembly may also include a mounting assembly adaptedto rigidly mount to at least one of the fluid inlet pipe or the fluidoutlet pipe within the enclosure. The mounting assembly holds the firstcoupling mechanism and the fluid inlet pipe in sealed engagement and thesecond coupling mechanism and the fluid outlet pipe in sealedengagement. The flow-control assembly may also include a handle disposedalong the center of gravity thereof at an upper portion of theflow-control assembly to allow easy removal of the flow-control assemblyfrom the pit assembly. In a preferred embodiment, the flow-controlassembly is a rigid, single-piece assembly, having all of the componentsthereof welded or otherwise rigidly connected together.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a side view of a flow-control assembly disposed within a pitassembly (illustrated in cross-section);

FIG. 2. is a top view of the flow-control assembly and the pit assemblyof FIG. 1 with the cover of the pit assembly removed;

FIG. 3 is a perspective view of the flow-control assembly of FIG. 1without the trim and pilots of the regulators;

FIG. 4 is a side view of regulator bodies of the flow-control assemblyof FIG. 1 illustrating, in phantom relief, the internal fluidpassageways therein; and

FIG. 5 is a side view of a second embodiment of a flow-control assemblydisposed within a pit assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, a flow-control assembly 10 constructedaccording to the present invention is disposed within a pit assembly 12having a lower portion or can 14 and a cover assembly 16 disposed on thecan 14. The cover assembly may be, for example, welded onto the can 14and opened in a hinged manner. The pit assembly 12 is preferablyconstructed for use underground with the cover assembly 16 beingdisposed in an accessible manner. A number of bolts 18, for example,four, may be loosened to allow the cover assembly 16 to be opened andthereby provide access to the flow-control assembly 10. Of course, anyother desired closure mechanism may be used with the pit assembly 12.FIG. 2 illustrates a top view of the flow-control assembly 10 with thecover assembly 16 of the pit assembly 12 opened.

As illustrated in FIG. 1, the flow-control assembly 10 is coupledbetween a fluid inlet pipe 22 coming from a fluid source and a fluidoutlet pipe 24 going to a fluid user. The fluid outlet pipe 24 includesan extension pipe 26 rigidly connected to the can 14 by a bracket 28(illustrated in detail in FIG. 2).

The flow-control assembly 10 is coupled to the fluid inlet pipe 22 via afirst coupling mechanism 29 having a female coupling end 30 (illustratedin FIG. 1 in cross-section) disposed on the flow-control assembly 10 anda male coupling end 31 disposed on the fluid inlet pipe 22. The malecoupling end 31 mates with the female coupling end 30 in a slidingmanner.

The female coupling end 30 is fluidly connected to a first regulator 32which, in turn, is fluidly connected to a second regulator 34. FIGS. 3and 4 illustrate the regulator bodies of, and the fluid passagewayswithin, the regulators 32 and 34 in more detail. The regulators 32 and34 may comprise pilot-operated regulators, such as the 399A regulatormanufactured by Fisher Controls Regulator Division, or may be any otherdesired type of regulator, valve or other control component forcontrolling fluid flow between the fluid inlet pipe 22 and the fluidoutlet pipe 24 in any desired manner. Of course the regulators 32 and 34may be the same or different types of regulators or other components asdesired.

The regulator 34 is rigidly connected to a 180 degree bend return pipe36 which, in turn, is coupled to the extension pipe 26 via a secondcoupling mechanism 37. The coupling mechanism 37 has a female couplingend 38 (illustrated in FIG. 1 in cross-section) disposed on the returnpipe 36 and a male coupling end 42 disposed on the extension pipe 26 sothat the male coupling end 42 mates with the female coupling end 38 in asliding manner. O-rings 44 are disposed within, for example, the femalecoupling ends 30 and 38 to seal the fluid line at those connectionpoints when the flow-control assembly 10 is properly installed withinthe pit assembly 12. If desired, the female coupling ends 30 and/or 38may be disposed on the pipes 22 and/or 26 while the male coupling endsmay be disposed on the flow-control assembly 10 in any fashion toprovide a sealed engagement between the flow-control assembly 10 and thefluid inlet pipe 22 and the fluid outlet pipe 24.

The flow-control assembly 10 may include a bracket 50 rigidly attachedto the regulator 34 and/or the return pipe 36. The bracket 50 isdesigned to mate with a bracket 52 rigidly attached to the an inner wallof the can 14 of the pit assembly 12. As illustrated in FIG. 2, thebracket 50 includes, for example, two bolt holes which accept nut andbolt assembles 54 associated with the bracket 52. The bolts of the nutand bolt assemblies 54 may be welded to the bracket 52 so that the holesof the bracket 50 can be inserted over these bolts to align theflow-control assembly 10 with the fluid inlet and fluid outlet pipes 22and 24. When the nuts of the nut and bolt assemblies 54 are attached tothe bolts and tightened, the flow-control assembly 10 is held rigidly inplace by the brackets 50 and 52 to assure a sealed engagement betweenthe ends of the coupling mechanisms 29 and 37.

A further bracket 56 (illustrated in slightly different positions inFIGS. 2 and 3) may be attached to the flow-control assembly 10 and usedto mount pilots 64 of the regulators 32 and 34 or to mount any otherdesired equipment. As illustrated in FIGS. 1 and 3, the flow-controlassembly 10 may also include a handle 68 welded or otherwise rigidlyattached to the flow-control assembly 10. Preferably, the handle 68 isattached to an upper portion of the flow-control assembly 10 such as thereturn pipe 36 when the flow-control assembly 10 is properly disposedwithin the pit assembly 12. Likewise, the handle 68 is preferablyattached to the flow-control assembly 10 along the line of the center ofgravity of the flow-control assembly 10 so that the flow-controlassembly 10 may be lowered into or removed from the pit assembly 12 in astable manner using only the handle 68.

Referring now to FIG. 5, a second flow-control assembly 69 isillustrated. The flow-control assembly 69 includes parts similar to theflow-control assembly 10, which are indicated by the same referencenumerals shown in FIG. 1. Thus, the flow control assembly 69 is similarto the assembly 10 of FIG. 1, however, it includes a mounting assembly74 instead of the mounting element 50. In addition, the enclosure 13 inwhich the flow-control assembly 69 is adapted to be disposed includes afirst bar 76 that is permanently and rigidly mounted (via, for example,a weld) to the fluid inlet pipe 22 and a second bar 78 that is alsopermanently and rigidly mounted to the fluid outlet pipe 24. Togetherthe mounting assembly 74 and the first and second bars 76 and 78 of theenclosure 13 provide an improved sealed engagement between the firstcoupling mechanism 29 and the fluid inlet pipe 22 and the secondcoupling mechanism 37 and the fluid outlet pipe 24.

The mounting assembly 74 may be adapted to rigidly mount to at least oneof the fluid inlet pipe 22 or the fluid outlet pipe 24 and holds thefirst coupling mechanism 29 and the fluid inlet pipe 22 in sealedengagement and the second coupling mechanism 37 and the fluid outletpipe 24 in sealed engagement. In FIG. 5 the mounting assembly 74 isrigidly mounted to both the fluid inlet pipe 22 and the fluid outletpipe 24.

The mounting assembly 74 includes a first tube 80 adapted to beremovably and rigidly mounted to the first bar 76 of the enclosure 13and a second tube 82 adapted to be removably and rigidly mounted to thesecond bar 78 of the enclosure 13.

Preferably the first and second tubes 80 and 82, respectively, of themounting assembly 74 are mounted to the first and second bars 76 and 78,respectively, of the enclosure 13 via fastener assemblies. The fastenerassemblies preferably include nut and bolt assemblies 86, 87 as shown inFIG. 5, but may also include nut and screw assemblies, nut and threadedstud assemblies, or other like devices. The first and second bars 76 and78 of the enclosure 13 each include a threaded bore 88 for accepting afirst end of a bolt of nut and bolt assembly 86. The first and secondtubes 80 and 82 of the mounting assembly 74 each include a through-holefor accepting a second end of the bolt of the nut and bolt assemblies 86therethrough.

The first ends of the bolts or other threaded fasteners, e.g., threadedstuds or screws, are first permanently mounted to the first and secondbars 76 and 78 of the enclosure via a liquid sealant. Specifically, theliquid sealant is applied to the first ends of the threaded bolts andthen the first ends of the threaded bolts are inserted into the bores 88of the first and second bars 76 and 78 of the enclosure, thereby forminga rigid and permanent connection between the bolts and the first andsecond bars 76 and 78 once the liquid sealant solidifies. To furtherreinforce this rigid connection, the nuts of the nut and bolt assemblies86 are then tightened.

After the first ends of the bolts have been permanently mounted to thefirst and second bars 76 and 78 of the enclosure 13, the second ends ofthe bolts are inserted through the through-holes of the first and secondtubes 80 and 82. The nuts of the nut and bolt assemblies 87 are thentightened, thereby rigidly and removably mounting the mounting assembly74 to the first and second bars 76 and 78 of the enclosure and, therebyto the pipes 22 and 24.

The flow-control assembly 69 may further include a plate 84 rigidlymounted to the first and second tubes 80 and 82. The first and secondtubes 80 and 82 of the mounting assembly 74 are thus also permanentlyand rigidly mounted to the 180 degree bend return pipe 36 via the plate84. The plate 84 includes, for example, four holes which accept nut andbolt assemblies used to rigidly mount any desired equipment, forexample, the pilots 64 of the regulators 32 and 34, to the plate 84 and,thus, to the flow-control assembly 69.

The handle 68 is preferably mounted to the plate 84 of the flow-controlassembly 69 along the line of the center of gravity of the flow-controlassembly 10 so that the flow-control assembly 10 may be lowered into orremoved from the pit assembly 12 in a stable manner (and relativelystraight manner) using only the handle 68.

In the embodiment of FIGS. 1-4, all of the components of theflow-control assembly 64, including the regulators 32 and 34, the returnpipe 36, the coupling ends 30 and 38, the brackets 50 and the handle 68are rigidly connected together via, for example, welds, to form asingle-piece flow-control assembly.

In the embodiment of FIG. 5, all of the components of the flow-controlassembly 69, including the regulators 32 and 34, the return pipe 36, thecoupling ends 30 and 38, the mounting assembly 74, and the handle 68 arerigidly connected together to form a single piece flow-control assembly.

When the flow-control assembly 10 or 69 is properly installed within thepit assembly 12 or 13 as illustrated in FIGS. 1 and 5, the pilots 64 ofthe regulators 32 and 34 may be connected to the extension pipe 26 via areturn pipe 70 held within the bracket 28. It is understood that thepilots 64 and/or other parts of the regulators 32 and 34 may beconnected to the return pipe 70 via tubing not illustrated in eitherFIG. 1 or FIG. 5. Likewise, the regulators 32, 34 and/or the pilots 64associated therewith may also be connected via tubing to an exhaustoutlet 72 disposed within a wall of the can 14. The exhaust outlet 72enables the flow-control assembly 10 or 69 to exhaust fluid out of thepit assembly 12 or 13 to prevent pressure buildup within the pitassembly 12 or 13. If desired, the exhaust outlet 72 may be fluidlyconnected to a recovery container or may be vented to the atmosphere.For the sake of simplicity, the tubing between the regulators 32, 34,the pilots 64, the fluid return pipe 70 and the exhaust outlet 72 arenot illustrated in FIGS. 1-5, it being understood that the connection ofthis tubing is known in the art and can be performed in any desiredmanner.

During operation of the flow-control assemblies 10 and 69 and the pitassemblies 12 or 13, one of the regulators 32 and 34, for exampleregulator 32, may be configured as a working regulator while the otherof the regulators, for example, regulator 34, may be configured as amonitoring regulator having a slightly higher downstream pressureset-point than the working regulator 32. When fluid is provided throughthe fluid inlet pipe 22 to the working regulator 32, the regulator 32controls the downstream fluid pressure at the fluid outlet pipe 24 toremain at a predetermined set-point value. When the working regulator 32operates correctly, the monitoring regulator 34 operates in an opencondition to allow the working regulator 32 to control the downstreamfluid pressure completely. If the working regulator 32 malfunctions andallows the downstream pressure to exceed the set-point pressure of themonitoring regulator 34, the monitoring regulator 34 thereafter operatesto limit the downstream pressure to the set-point value of themonitoring regulator 34. If desired, a safety slam-shut valve may bedisposed between the working regulator 32 and the fluid inlet pipe 22.This slam-shut device may detect the downstream pressure and shut offthe fluid flow through the flow-control assembly 10, 69 if thedownstream pressure reaches a predetermined amount above the set-pointvalue of the monitoring regulator 34 (which occurs if both the workingregulator 32 and the monitoring regulator 34 malfunction).

Although the flow-control assemblies 10, 69 are described herein asincluding two regulators disposed in series, it is considered that anyother number and/or any desired types of fluid flow control components,such as valves, filters, pressure control devices, etc. may beintegrated into or used to form a flow-control assembly according to theprinciples described herein for any desired fluid flow controloperation.

As will be evident to those skilled in the art, the flow-controlassemblies 10 and 69 can be easily and quickly removed from the pitassembly 12 or 13 by first closing isolation valves upstream of thefluid inlet pipe 22 and downstream of the fluid outlet pipe 24, and thenloosening the bolts 18, opening the cover assembly 16 to expose theflow-control assembly 10 or 69, removing the nuts from the nut and boltassemblies 54, 87, removing the tubing between the regulators 32, 34,the pipe 70 and the outlet 72, and pulling on the handle 68 until theflow-control assembly 10 or 69 disengages from the fluid inlet and thefluid outlet pipes 22 and 24. A new and identical flow-control assembly10 or 69 having functioning components may then be lowered into the can14 until the coupling ends 30 and 38 of the new flow-control assembly 10or 69 contact and completely engage the coupling ends 31 and 42 on thepipes 22 and 26 and so that either the holes in the bracket 50 aredisposed around the bolts of the nut and bolt assemblies 54 or thethrough-holes of the first and second tubes 80 and 82 are disposedaround the bolts of the nut and bolt assemblies 87. Thereafter, tubingis connected between the regulators 32, 34, the pipe 70 and the outlet72 and fluid flow is reestablished through the pit assembly 12 or 13 byopening the upstream and downstream isolation valves. The components ofthe removed flow-control assembly 10 may be tested, repaired and/orreplaced at leisure in a suitable working environment.

Because of the ease and quickness associated with removing and replacingthe flow-control assembly 10 or 69, minimal traffic tie-ups are createdduring station testing and maintenance. Also, as will be evident, aservice provider can quickly remove and replace the flow-controlassembly 10 or 69 without having to crawl down into the pit assembly 12or 13 and without having to remove and replace numerous bolts and nutassemblies or other connector fittings. This advantage enables the pitassembly 12 or 13 to be smaller because the pit assembly 12 or 13 doesnot need to provide space for a service provider to enter the pitassembly when testing, disassembling and reassembling the fluid flowcomponents within the pit assembly. Removal of the need to crawl downinto a pit assembly to test or maintain equipment provides a significantsafety benefit.

Notably, one of the reasons that the flow-control assembly 10 or 69 isso easily replaced is that the coupling ends 30 and 38 simultaneouslydisconnect from or connect to the fluid inlet pipe 22 and the extensionpipe 26 by being moved in the same direction. In effect, one motion(e.g., pulling on the handle 68 or lowering the flow-control assembly 10or 69 into the pit assembly 12 or 13) decouples the flow-controlassembly 10 or 69 from or couples the flow-control assembly 10 or 69 toboth the fluid inlet pipe 22 and the extension pipe 26 without having toremove any bolt and nut assemblies at the connection points between theflow-control assembly 10 or 69 and the rest of the fluid flow line.Furthermore, due to the placement of the brackets 50 and 52 in the firstembodiment of the flow-control assembly 10 and the placement of themounting assembly 74 and the first and second bars 76 and 78 of theenclosure in the second embodiment of the flow-control assembly 69, aservice person does not need to get into the pit assembly 12 or 13 totest, remove or replace the flow-control assembly 10 or 69, whichshortens the time needed to test, remove or replace the fluid flowcontrol components within the pit assembly 12 or 13.

While the coupling mechanisms 29 and 37 have been illustrated as havingfemale and male ends that sealingly engage each other, other types ofsealable coupling members may be used instead. Preferably however, thecouplings used with the flow-control assembly 10 or 69 will not use nutand bolt or other types of fittings that take a protracted amount oftime to engage or disengage and/or which require a service person toreach down into or crawl down into the pit assembly 12 or 13 to engageor disengage.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only, and notto be limiting of the invention, it will be apparent to those ofordinary skill in the art that changes, additions and/or deletions maybe made to the disclosed embodiments without departing from the spiritand scope of the invention.

What is claimed is:
 1. A fluid flow assembly adapted to be disposed inan enclosure having an opening and having a fluid inlet pipe with afluid inlet pipe end and a fluid outlet pipe with a fluid outlet pipeend disposed in the enclosure, the fluid flow assembly comprising: afirst coupling mechanism adapted to engage the fluid inlet pipe end; asecond coupling mechanism adapted to engage the fluid outlet pipe end; afluid flow control assembly rigidly connected between the first andsecond coupling mechanisms; and a mounting assembly rigidly mounted tothe fluid flow assembly and adapted to rigidly mount to at least one ofthe fluid inlet pipe or the fluid outlet pipe at a location away fromthe fluid inlet pipe end and the fluid outlet pipe end, wherein themounting assembly holds the first coupling mechanism and the fluid inletpipe in sealed engagement and the second coupling mechanism and thefluid outlet pipe in sealed engagement.
 2. The fluid flow assembly ofclaim 1, wherein the mounting assembly is adapted to rigidly mount toboth the fluid inlet pipe and the fluid outlet pipe.
 3. The fluid flowassembly of claim 1, wherein the enclosure includes a first elementpermanently and rigidly mounted to the fluid inlet pipe and a secondelement permanently and rigidly mounted to the fluid outlet pipe,wherein the mounting assembly includes a first member adapted to beremovably, rigidly mounted to the first element and a second memberadapted to be removably, rigidly mounted to the second element.
 4. Thefluid flow assembly of claim 3, wherein the first member of the mountingassembly is adapted to accept a threaded fastener.
 5. The fluid flowassembly of claim 3, wherein the second member of the mounting assemblyis adapted to accept a threaded fastener.
 6. The fluid flow assembly ofclaim 3, further comprising a plate rigidly, mounted between the firstand second members of the mounting assembly.
 7. The fluid flow assemblyof claim 1, further comprising a handle disposed between the first andsecond coupling mechanisms at a center of gravity of the fluid flowassembly, the handle located in proximity to the opening so that thehandle can be reached by a service person through the opening.
 8. Thefluid flow assembly of claim 1, further including a fluid flowpassageway that is connected between the first coupling mechanism andthe second coupling mechanism and that includes a one-hundred and eightydegree bend therein.
 9. The fluid flow assembly of claim 1, wherein thefirst and second coupling mechanisms each includes a female coupling endadapted to be disposed over a male coupling end located on the fluidinlet pipe end or the fluid outlet pipe end.
 10. The fluid flow assemblyof claim 1, wherein the fluid flow control element comprises aregulator.
 11. The fluid flow assembly of claim 1, wherein the fluidflow control element comprises two control elements rigidly connectedtogether.
 12. The fluid flow assembly of claim 11, wherein each of thecontrol elements is a pilot operated regulator.
 13. The fluid flowassembly of claim 1, wherein the first and second coupling mechanismsare each oriented to open in a first direction such that movement of thefluid flow assembly in a second direction disengages the first couplingmechanism from the fluid inlet pipe while disengaging the secondcoupling mechanism from the fluid outlet pipe.
 14. A fluid deliveryassembly, comprising: an enclosure having an opening; a fluid inlet pipehaving a fluid inlet pipe end disposed within the enclosure; a fluidoutlet pipe having a fluid outlet pipe end disposed within theenclosure; and a rigid fluid flow assembly adapted to be disposed withinthe enclosure and to be removably coupled between the fluid inlet pipeand the fluid outlet pipe, the fluid flow assembly including, a firstcoupling mechanism adapted to engage the fluid inlet pipe end, a secondcoupling mechanism adapted to engage the fluid outlet pipe end, a fluidflow control assembly coupled between the first and second couplingmechanisms, and a mounting assembly rigidly mounted to the fluid flowassembly and adapted to rigidly mount to both the fluid inlet pipe at alocation away from the fluid inlet pipe end and the fluid outlet pipe ata location away from the fluid outlet pipe end, wherein the mountingassembly holds the first coupling mechanism and the fluid inlet pipe insealed engagement and the second coupling mechanism and the fluid outletpipe in sealed engagement.
 15. The fluid delivery assembly of claim 14,further including a first element permanently and rigidly mounted to thefluid inlet pipe and a second element permanently and rigidly mounted tothe fluid outlet pipe and wherein the mounting assembly includes a firstmember adapted to be removably, rigidly mounted to the first element anda second member adapted to be removably, rigidly mounted to the secondelement.
 16. The fluid flow assembly of claim 14, further comprising ahandle disposed between the first and second coupling mechanisms at acenter of gravity of the fluid flow assembly, the handle being locatedin proximity to the opening so that the handle can be reached by aservice person through the opening.
 17. The fluid flow assembly of claim14, wherein the first and second coupling mechanisms are each orientedto open in a first direction such that movement of the fluid flowassembly in a second direction disengages the first coupling mechanismfrom the fluid inlet pipe while disengaging the second couplingmechanism from the fluid outlet pipe.